ARCHITECTURE may be described as building at its best, and when we talk of the architecture of any city or country we mean its best, noblest, or most beautiful buildings; and we imply by the use of the word that these buildings possess merits which entitle them to rank as works of art.
The architecture of the civilised world can be best understood by considering the great buildings of each important nation separately. The features, ornaments, and even forms of ancient buildings differed just as the speech, or at any rate the literature, differed. Each nation wrote in a different language, though the books may have been  devoted to the same aims; and precisely in the same way each nation built in a style of its own, even if the buildings may have been similar in the purposes they had to serve. The division of the subject into the architecture of Egypt, Greece, Rome, &c., is therefore the most natural one to follow.
But certain broad groups, rising out of peculiarities of a physical nature, either in the buildings themselves or in the conditions under which they were erected, can hardly fail to be suggested by a general view of the subject. Such, for example, is the fourfold division to which the reader’s attention will now be directed.
All buildings, it will be found, can be classed under one or other of four great divisions, each distinguished by a distinct mode of building, and each also occupying a distinct place in history. The first series embraces the buildings of the Egyptians, the Persians, and the Greeks, and was brought to a pitch of the highest perfection in Greece during the age of Pericles. All the buildings erected in these countries during the many centuries which elapsed from the earliest Egyptian to the latest Greek works, however they may have differed in other respects, agree in this—that the openings, be they doors, or be they spaces between columns, were spanned by beams of wood or lintels of stone (Fig. 1). Hence this architecture is called architecture of the beam, or, in more formal language, trabeated architecture. This mode of covering spaces required that in buildings of solid masonry, where stone or marble lintels were employed, the supports should not be very far apart, and this circumstance led to the frequent use of rows of columns. The architecture of this period is accordingly sometimes called columnar, but it has no exclusive claim to the  epithet; the column survived long after the exclusive use of the beam had been superseded, and the term columnar must accordingly be shared with buildings forming part of the succeeding series.
The second great group of buildings is that in which the semicircular arch is introduced into construction, and  used either together with the beam, or, as mostly happened, instead of the beam, to span the openings (Fig. 2). This use of the arch began with the Assyrians, and it reappeared in the works of the early Etruscans. The round-arched series of styles embraces the buildings of the Romans from their earliest beginnings to their decay; it also includes the two great schools of Christian architecture which were founded by the Western and the Eastern Church respectively,—namely, the Romanesque, which, originating in Rome, extended itself through Western Europe, and lasted till the time of the Crusades, and the Byzantine, which spread from Constantinople over all the countries in which the Eastern (or Greek) Church flourished, and which continues to our own day.
The third group of buildings is that in which the pointed arch is employed instead of the semicircular arch to span the openings (Fig. 3). It began with the rise of Mohammedan architecture in the East, and embraces all the buildings of Western Europe, from the time of the First Crusade to the revival of art in the fifteenth century.  This great series of buildings constitutes what is known as Pointed, or, more commonly, as Gothic architecture.
The fourth group consists of the buildings erected during or since the Renaissance (i.e. revival) period, and is marked by a return to the styles of past ages or distant countries for the architectural features and ornaments of buildings; and by that luxury, complexity, and ostentation which, with other qualities, are well comprehended under the epithet Modern. This group of buildings forms what is known as Renaissance architecture, and extends from the epoch of the revival of letters in the fifteenth century, to the present day.
The first two of these styles—namely, the architecture of the beam, and that of the round arch—are treated of in this little volume. They occupy those remote times of pagan civilisation which may be conveniently included under the broad term Ancient; and the better known work of the Greeks and Romans—the classic nations—and they extend over the time of the establishment of Christianity down to the close of that dreary period not incorrectly termed the Dark ages. Ancient, Classic, and early Christian architecture is accordingly an appropriate title for the main subjects of this volume, though, for the sake of convenience, some notices of Oriental architecture have been added. Gothic and Renaissance architecture form the subjects of the companion volume.
It may excite surprise that what appears to be so small a difference as that which exists between a beam, a round arch, or a pointed arch, should be employed in order to distinguish three of the four great divisions. But in reality this is no pedantic or arbitrary grouping. The mode in which spaces or openings are covered lies at the root of most of the essential differences between styles of  architecture, and the distinction thus drawn is one of a real, not of a fanciful nature.
Every building when reduced to its elements, as will be done in both these volumes, may be considered as made up of its (1) floor or plan, (2) walls, (3) roof, (4) openings, (5) columns, and (6) ornaments, and as marked by its distinctive (7) character, and the student must be prepared to find that the openings are by no means the least important of these elements. In fact, the moment the method of covering openings was changed, it would be easy to show, did space permit, that all the other elements, except the ornaments, were directly affected by the change, and the ornaments indirectly; and we thus find such a correspondence between this index feature and the entire structure as renders this primary division a scientific though a very broad one. The contrast between the trabeated style and the arched style may be well understood by comparing the illustration of the Parthenon which forms our frontispiece, or that of the great temple of Zeus at Olympia (Fig. 4), with the exterior of the Colosseum at Rome (Fig. 5), introduced here for the purposes of this comparison.
A division of buildings into such great series as these cannot, however, supersede the more obvious historical and geographical divisions. The architecture of every ancient country was partly the growth of the soil, i.e. adapted to the climate of the country, and the materials found there, and partly the outcome of the national character of its inhabitants, and of such influences as race, colonisation, commerce, or conquest brought to bear upon them. These influences produced strong distinctions between the work of different peoples, especially before the era of the Roman Empire. Since that  period of universal dominion all buildings and styles have been influenced more or less by Roman art. We accordingly find the buildings of the most ancient nations separated from each other by strongly marked lines of demarcation, but those since the era of the Empire showing a considerable resemblance to one another. The circumstance that the remains of those buildings only which received the greatest possible attention from their builders have come down to us from any remote antiquity, has perhaps served to accentuate the differences between different styles, for these foremost buildings were not intended to serve the same purpose in all countries. Nothing but tombs and temples have survived in Egypt. Palaces only have been rescued from the decay of Assyrian and Persian cities; and temples, theatres, and places of public assembly are the chief, almost the only remains of architecture in Greece.
A strong contrast between the buildings of different ancient nations rises also from the differing point of view for which they were designed. Thus, in the tombs and, to a large extent, the temples of the Egyptians, we find structures chiefly planned for internal effect; that is to say, intended to be seen by those admitted to the sacred precincts, but only to a limited extent appealing to the admiration of those outside. The buildings of the Greeks, on the other hand, were chiefly designed to please those who examined them from without, and though no doubt some of them, the theatres especially, were from their very nature planned for interior effect, by far the greatest works which Greek art produced were the exteriors of the temples.
The works of the Romans, and, following them, those of almost all Western Christian nations, were designed  to unite external and internal effect; but in many cases external was evidently most sought after, and, in the North of Europe, many expedients—such, for example, as towers, high-pitched roofs, and steeples—were introduced into architecture with the express intention of increasing external effect. On the other hand, the Eastern styles, both Mohammedan and Christian, especially when practised in sunny climates, show in many cases a comparative disregard of external effect, and that their architects lavished most of their resources on the interiors of their buildings.
Passing allusions have been made to the influence of climate on architecture; and the student whose attention has been once called to this subject will find many interesting traces of this influence in the designs of buildings erected in various countries. Where the power of the sun is great, flat terraced roofs, which help to keep buildings cool, and thick walls are desirable. Sufficient light is admitted by small windows far apart. Overhanging eaves, or horizontal cornices, are in such a climate the most effective mode of obtaining architectural effect, and accordingly in the styles of all Southern peoples these peculiarities appear. The architecture of Egypt, for example, exhibited them markedly. Where the sun is still powerful, but not so extreme, the terraced roof is generally replaced by a sloping roof, steep enough to throw off water, and larger openings are made for light and air; but the horizontal cornice still remains the most appropriate means of gaining effects of light and shade. This description will apply to the architecture of Italy and Greece. When, however, we pass to Northern countries, where snow has to be encountered, where light is precious, and where the sun is low in the heavens for the  greater part of the day, a complete change takes place. Roofs become much steeper, so as to throw off snow. The horizontal cornice is to a large extent disused, but the buttress, the turret, and other vertical features, from which a level sun will cast shadows, begin to appear; and windows are made numerous and spacious. This description applies to Gothic architecture generally—in other words, to the styles which rose in Northern Europe.
The influence of materials on architecture is also worth notice. Where granite, which is worked with difficulty,  is the material obtainable, architecture has invariably been severe and simple; where soft stone is obtainable, exuberance of ornament makes its appearance, in consequence of the material lending itself readily to the carver’s chisel. Where, on the other hand, marble is abundant and good, refinement is to be met with, for no other building material exists in which very delicate mouldings or very slight or slender projections may be employed with the certainty that they will be effective. Where stone is scarce, brick buildings, with many arches, roughly constructed cornices and pilasters, and other peculiarities both of structure and ornamentation, make their appearance, as, for example, in Lombardy and North Germany. Where materials of many colours abound, as is the case, for example, in the volcanic districts of France, polychromy is sought as a means of ornamentation. Lastly, where timber is available, and stone and brick are both scarce, the result is an architecture of which both the forms and the ornamentation are entirely dissimilar to those proper to buildings of stone, marble, or brick, as may be seen by a glance at our illustration of an early Scandinavian church built of timber (Fig. 6), which presents forms appropriate to a timber building as being easily constructed of wood, but which would hardly be suitable to any other material whatever.